The present invention relates to the hinges, and more particularly to a structure improvement of spring hinge, which is to place incision holes at the surface of the tension adjustment stands, and insert the insertion portions at two ends of the spring into these holes to increase the stability of the positioning of the torque spring, and to reduce the noise when operate, the difficulties in manufacturing and assembling, moreover, the tension adjustment stand made of plastic composite material because of the high durability, in order to avoid having the metal tubing part, and to simplify the composition such, and hence, reduce the difficulties in production and assembly.
FIG. 1 shows the prior art of a regular hinge used in large-scale heavy duty doors. This kind of the hinge is composed of a double-tube base plate 10, a pair of torque springs 12 placed inner of the tubes 11, and a pair of tension adjustment stands 13, 13' placed at the ends of the tubes 11. Place the ends 121 of the torque spring 12 inner the bottom of the trench, at the perimeter of the tension adjustment stand 13, setup a plurality of adjustment holes 132 at equal distance in order to use a double-headed pin 14 to adjust the tension of the spring 12. Also, there are a pair of turning flanges 20 that utilize the tips of the rods 22 to connect the tubes 11 at turned angle of the flanges 21, and then, fasten the ends of the tubes 11 with a pair of threaded caps 23. FIG. 2 shows an assembled spring hinge of FIG. 1. This kind of the spring hinge utilizes the torque spring to store the tensile strength in order to accomplish the function of automatic door closing. However, this design included the following disadvantages:
1) The tension adjustment stand is made of metal, the manufacturing of such is difficult and expensive. PA1 2) Furthermore, the stair-like hard surface is closely attached to the interior walls of the tubes 11, after constant torque and turns, the diameters of the tubes will expand, which in turn, causes the hinge to disfigure. PA1 3) Because the axle tips 22 are also made of metal, and the axles pass through the center of the tension adjustment base 13. Furthermore, the a pair of tips of the torque springs 22 only rest on the groves of the tension adjustment bases 13, that is, the a pair of ends of the torque springs circle around the stair-like surface of the tension adjustment bases. So when the torque spring 22 turns against the tension adjustment base, the movements are apparent and the contacts between the axle tips 22 and the interior walls create noises. If cracks appear at the trench 131, it must be damaged by the torque of the spring 12.
Based on the aforementioned disadvantages of the prior art, the applicant reinvented an improved spring hinge which had already granted patent by the U.S. PTO (Application Filed Number 08/590,631), please refer to FIGS. 3 and 4, which consists of a rectangular base plate 30 with a pair of tubes at the sides, as a unit, to form a pair of guiding tubes 31, each of the guiding tube 31 contains a torque spring 32, a ring cap 35 with a protruding lip 351 that matches with the diameter of the guiding tube 31, and a first tension adjustment stand 33 made of plastic, which further contains a small metal tube 34 clips onto one end of the torque spring 32. The first tension adjustment stand 33 inserts into a tip of the tube 31 and utilizes its cylindrical main body to rest on the ring cap 35, a second tension adjustment stand 36, made of plastic, directly inlays into the bottom of the guiding tube 31 where it also contains a small metal tube 34' for clipping unto the other end of the torque spring 32. A pair of flanges 40 using their turned angle protrusions 41 to hold the exteriors of the first and second tension adjustment stands 33 and 36, and utilizing the tip of an axle rods 50 and a threaded cap 52 to connect to the second guiding tube 31. A pair of adjustment pins 60 are inserted into an adjustment holes 336 at the perimeter of the first adjustment stand 33 for adjustment of the tension at the torque spring 32 and to press against the ends of the flanges 40.
With the aforementioned improvement, the spring hinge will smoothly closes the door automatically without any noise or distortion. These improved portions are enough to ensure the structural stability, enhance durability, and increase actual functions. However, though the first and second adjustment stands 33 and 36 are made of enhanced plastic, still the inserted small metal tubes 34 and 34' are necessary to sustain the opposite force exerted at the ends of the torque spring 32. Otherwise, under the constant torque resistance from the torque spring 32, the ends of the spring is likely to damage the first and second adjustment stands 33 and 36. The small metal tubes 34 and 34' are actually made of sheet metal bend into a tubular shape. When they are inserted into the first and second adjustment stands 33 and 36, because of their elastic nature, they are closely fitted into the first and second adjustment stands 33 and 36, hence they won't fall off the first and second adjustment stands 33 and 36. The small metal tubes 34 and 34' are difficult to manufacture, and the assembling of these tubes into the first and second adjustment stands 33 and 36 are quite difficult. Moreover, the end of the spring of the torque spring 32 winds into the side opening of the small metal tubes 34 and 34', and positioned through these small metal tubes 34 and 34'. When the torque spring 32 turns, because of the tension is concentrate in the end of the spring 32, the end of the spring 32 will fall off easily and cause a separation with the small metal tubes 34 and 34' to cause any possible dangerous. The positioning of the torque spring 32 is not stable nor is it reliable, and the part of the stands 33 and 36 which touch with the end of the spring 32 will distract because of the torque spring 32 is in operate.
The present invention is arisen to militate and/or obviate the aforediscussed disadvantages in order to provide a new and novel structure hereinafter.